It is generally agreed that the main function of food is to repair the tissues of the body. Other effects are present, such as pleasure and sociability, but its chief benefit is reparative, so we may well regard the subject from a strictly utilitarian standpoint and inquire how we may produce the highest efficiency from our eating. Some of the important questions about eating are, how much to eat, what kind of food to eat, when to eat, what are the most favorable conditions for eating?
The quantity of food to be taken varies with the demands of the individual appetite and the individual powers of absorption. In general, one who is engaged in physical labor needs more, because of increased appetite and increased waste of tissues. So a farm-hand needs more food than a college student, whose work is mostly indoors and sedentary. Much has been said recently about the ills of overeating. One of the most enthusiastic defenders of a decreased diet is Mr. Horace Fletcher, who, by the practice of protracted mastication, "contrives to satisfy the appetite while taking an exceptionally small amount of food. Salivary digestion is favored and the mechanical subdivision of the food is carried to an extreme point. Remarkably complete digestion and absorption follow. By faithfully pursuing this system Mr. Fletcher has vastly bettered his general health, and is a rare example of muscular and mental power for a man above sixty years of age. He is a vigorous pedestrian and mountain-climber and holds surprising records for endurance tests in the gymnasium.
"The chief gain observed in his case, as in others which are more or less parallel, is the acquiring of immunity to fatigue, both muscular and central. It is not claimed that the sparing diet confers great strength for momentary efforts—'explosive strength,' as the term goes—but that moderate muscular contractions may be repeated many times with far less discomfort than before. The inference appears to be that the subject who eats more than is best has in his circulation and his tissues by-products which act like the muscular waste which is normally responsible for fatigue. According to this conception he is never really fresh for his task, but is obliged to start with a handicap. When he reduces his diet the cells and fluids of his body free themselves of these by-products and he realizes a capacity quite unguessed in the past.
"The same assumption explains the fact mentioned by Mr. Fletcher, that the hours of sleep can be reduced decidedly when the diet is cut down. It would seem as though a part of our sleep might often be due to avoidable auto-intoxication. If one can shorten his nightly sleep without feeling the worse for it this is an important gain."
But the amount of food is probably not so important as the kind. Foods containing much starch, as potatoes and rice, may ordinarily be taken in greater quantities than foods containing much protein, such as meats and nuts. So our problem is not so much concerned with quantity as with the choice of kinds of food. Probably the most favorable distribution of foods for students is a predominance of fruits, coarse cereals, starch and sugar and less prominence to meats. Do not begin the day's study on a breakfast of cakes. They are a heavy tax upon the digestive powers and their nutritive value is low. The mid-day meal is also a crucial factor in determining the efficiency of afternoon study, and many students almost completely incapacitate themselves for afternoon work by a too-heavy noon meal. Frequently an afternoon course is rendered quite valueless because the student drowses through the lecture soddened by a heavy lunch. One way of overcoming this difficulty is by dispensing with the mid-day meal; another way is to drink a small amount of coffee, which frequently keeps people awake; but these devices are not to be universally recommended.
The heavy meal of a student may well come at evening. It should consist of a varied assortment of foods with some liquids, preferably clear soup, milk and water. Meat also forms a substantial part of this meal, though ordinarily it should not be taken more than once a day. Much is heard nowadays about the dangers of excessive meat-eating and the objections are well-founded in the case of brain-workers. The undesirable effects are "an unprofitable spurring of the metabolism— more particularly objectionable in warm weather—and the menace of auto-intoxication." Too much protein, found in meat, lays a burden upon the liver and kidneys and when the burden is too great, wastes, which cannot be taken care of, gather and poison the blood, giving rise to that feeling of being "tired all over" which is so inimical to mental and physical exertion. When meat is eaten, care should be taken to choose right kinds. "Some kinds of meat are well known to occasion indigestion. Pork and veal are particularly feared. While we may not know the reason why these foods so often disagree with people, it seems probable that texture is an important consideration. In both these meats the fibre is fine, and fat is intimately mingled with the lean. A close blending of fat with nitrogenous matter appears to give a fabric which is hard to digest. The same principle is illustrated by fat-soaked fried foods. Under the cover of the fat, thorough-going bacterial decomposition of the proteins may be accomplished with the final release of highly poisonous products. Attacks of acute indigestion resulting from this cause are much like the so-called ptomaine poisoning."
Much of the benefit of meat may be secured from other foods. Fat, for example, may be obtained from milk and butter freed from the objectionable qualities of the meat-fibre. In this connection it is important to call attention to the use of fried fat. Avoid fat that is mixed with starch particles in such foods as fried potatoes and pie-crust.
The conditions during meals should always be as pleasant as possible. This refers both to physical surroundings and mental condition. "The processes occurring in the alimentary canal are greatly subject to influences radiating from the brain. It is especially striking that both the movements of the stomach and the secretion of the gastric juice may be inhibited as a result of disturbing circumstances. Intestinal movements may be modified in similar fashion."
"Cannon has collected various instances of the suspension of digestion in consequence of disagreeable experiences, and it would be easy for almost anyone to add to his list. He tells us, for example, of the case of a woman whose stomach was emptied under the direction of a specialist in order to ascertain the degree of digestion undergone by a prescribed breakfast. The dinner of the night before was recovered and was found almost unaltered. Inquiry led to the fact that the woman had passed a night of intense agitation as the result of misconduct on the part of her husband. People who are seasick some hours after a meal vomit undigested food. Apprehension of being sick has probably inhibited the gastric activities.
"Just as a single occasion of painful emotion may lead to a passing digestive disturbance, so continued mental depression, worry, or grief may permanently impair the working of the (alimentary) tract and undermine the vigor and capacity of the sufferer. Homesickness is not to be regarded lightly as a cause of malnutrition. Companionship is a powerful promoter of assimilation. The attractive serving of food, a pleasant room, and good ventilation are of high importance. The lack of these, so commonly faced by the lonely student or the young man making a start in a strange city, may be to some extent counteracted by the cultivation of optimism and the mental discipline which makes it possible to detach one's self from sordid surroundings."
Almost as important as eating is drinking, for liquids constitute the "largest item in the income" of the body. Free drinking is recommended by physiologists, the beneficial results being, "the avoidance of constipation, and the promotion of the elimination of dissolved waste by the kidneys and possibly the liver." In regard to the use of water with meals, a point upon which emphatic cautions were formerly offered, recent experiments have failed to show any bad effects from this, and the advice is now given to drink "all the water that one chooses with meals." Caution should be observed, however, about introducing hot and cold liquids into the stomach in quick succession.
Other liquids have been much discussed by dietitians, especially tea and coffee. "These beverages owe what limited food value they have to the cream and sugar usually mixed with them. They give pleasure by their aroma, but they are given a peculiar position among articles of diet by the presence in them of the compound caffein, which is distinctly a drug. It is a stimulant to the heart, the kidneys, and the central nervous system."
"Individual susceptibility to the action of caffein varies greatly. Where one person notices little or no reaction after a cup of coffee, another is exhilarated to a marked degree and hours later may find himself lying sleepless with tense or trembling muscles, a dry, burning skin, and a mind feverishly active. Often it is found that a more protracted disturbance follows the taking of coffee with cream than is caused by black coffee.
"It is too much to claim that the use of tea and coffee is altogether to be condemned. Many people, nevertheless, are better without them. For all who find themselves strongly stimulated it is the part of wisdom to limit the enjoyment of these decoctions to real emergencies when uncommon demands are made upon the endurance and when for a time hygienic considerations have to be ignored. If young people will postpone the formation of the habit they will have one more resource when the pressure of mature life becomes severe."
Before concluding this discussion a word might be added concerning the relation between fasting and mental activity. Prolonged abstinence from food frequently results in highly sharpened intellectual powers. Numerous examples of this are found in the literature of history and biography; many actors, speakers and singers habitually fast before public performances. There are some disadvantages to fasting, especially loss of weight and weakness, but when done under the direction of a physician, fasting has been known to produce very beneficial effects. It is mentioned here because it has such marked effects in speeding up the mental processes and clearing the mind; and the well-nourished student may find the practice a source of mental strength during times of stress such as examinations.
"About one-third of an average human life is passed in the familiar and yet mysterious state which we call sleep. From one point of view this seems a large inroad upon the period in which our consciousness has its exercise; a subtraction of twenty-five years from the life of one who lives to be seventy-five. Yet we know that the efficiency and comfort of the individual demand the surrender of all this precious time. It has often been said that sleep is a more imperative necessity than food, and the claim seems to be well founded." It is quite likely that some students indulge in too much sleep. This may sometimes be due to laziness, but frequently it is due to actual intoxication, from an excess of food which results in the presence of poisonous "narcotizing substances absorbed from the burdened intestine". This theory is rendered tenable by the fact that when the diet is reduced the hours of sleep may be reduced. If one is in good health, it seems right to expect that one should be able to arise gladly and briskly upon awaking. By all means do not indulge yourself in long periods of lying in bed after a good night's rest. If we examine the physical and physiological conditions of sleep we shall better understand its hygiene. Sleep is a state in which the tissues of the body which have been used up may be restored. Of course some restoration of broken-down tissue takes place as soon as it begins to wear out, but so long as the body keeps working, the one process can never quite compensate for the other, so there must be a periodic cessation of activity so that the energies of the body may be devoted to restoration. Viewing sleep as a time when broken-down bodily cells are restored, we see that we tax the energies of the body less if we go to sleep each day before the cells are entirely depleted. That is the significance of the old teaching that sleep before midnight is more efficacious than sleep after midnight. It is not that there is any mystic virtue in the hours before twelve, but that in the early part of the evening the cells are not so nearly exhausted as they are later in the evening, and it is much easier to repair them in the partially exhausted stage than it is in the completely exhausted stage. For this reason, a mid-day nap is often effective, or a short nap after the evening dinner. By thus catching the cells at an early stage of their exhaustion, they can be restored with comparative ease, and more energy will be available for use during the remainder of the working hours.
A problem that may occasionally trouble a student is sleeplessness and we may properly consider here some of the ways of avoiding it. One prime cause of sleeplessness is external disturbance. The disturbance may be visual. Although it is ordinarily thought that if the eyes are closed, no visual disturbances can be sensed, nevertheless, as a matter of fact the eye-lids are not wholly opaque. Sight may be obtained through them, as you may prove by closing your eyes and moving your fingers before them. The lids transmit light to the retina and it is quite likely that you are frequently awakened by a beam of light falling upon your closed eye-lids. For this reason, one who is inclined to be wakeful should shut out from the bed-room all avenues whereby light may enter as a distraction.
The temperature sense is also a source of distraction in sleep, and it is a common experience to be awakened by extreme cold. The ears, too, may be the source of disturbance in sleep; for even though we are asleep, the tympanic membrane is always exposed to vibrations of air. In fact, stimuli are continually playing upon the sense-organs and are arousing nervous currents which try to break over the boundaries of sleep and impress themselves upon the brain.
For this reason, one who wishes to have untroubled sleep should remove all possible distractions.
But apart from external distractions, wakefulness may still be caused by distractions from within. Troublesome ideas may be present and persist in keeping one awake. This means that brain activity has been started and needs suppression. Various devices have been suggested. One is to eat something very light, just enough to draw the surplus blood, which excites the brain, away from the brain to the digestive tract. This advice should be taken with caution, however, for eating just before retiring may use up in digestion much of the energy needed in repairing the body, and may leave one greatly fatigued in the morning.
One way to relieve the mind of mental distractions is to fill it with non-worrisome, restful thoughts. Read something light, a restful essay or a non-exciting story, or poetry. Another device is to bathe the head in cold water so as to relieve congestion of blood in the brain. A tepid or warm bath is said to have a similar effect.
Dreams constitute one source of annoyance to many, and while they are not necessarily to be avoided, still they may disturb the night's rest. We may avoid them in some measure by creating conditions free from sensory distractions, for many of our dreams are direct reflections of sensations we are experiencing at the moment. A dream with an arctic setting may be the result of becoming uncovered on a cold night. To use an illustration from Ellis: "A man dreams that he enlists in the army, goes to the front, and is shot. He is awakened by the slamming of a door. It seems probable that the enlistment and the march to the field are theories to account for the report which really caused the whole train of thought, though it seemed to be its latest item." Such dreams may be partially eliminated by care in arranging conditions so that there will be few distractions. Especially should they be guarded against in the later hours of the sleep, for we do not sleep so soundly after the first two hours as we do before, and stimuli can more easily impress themselves and affect the brain.
Before leaving the subject of sleep, we should note the benefit to be derived from regularity in sleep. All Nature seems to move rhythmically and sleep is no exception. Insomnia may be treated by means of habituating one's self to get sleepy at a certain time, and there is no question that the rising process may be made easier if one forms the habit of arising at the same time every morning. To rhythmize this important function is a long step towards the efficient life.
Brain workers do not ordinarily get all the exercise they should. Particularly is this true of some conscientious students who feel they must not take any time from their study. But this denotes a false conception of mental action. The human organism needs exercise. Man is not a disembodied spirit; he must pay attention to the claims of the body. Indeed it will be found that time spent in exercise will result in a higher grade of mental work. This is recognized by colleges and universities by the requirement of gymnasium work, and the opportunity should be welcomed by the student. Inasmuch as institutions generally give instruction in this subject, we need not go specifically into the matter of exercises. Perhaps the only caution that need be urged is that against the excessive participation in such exhausting games as foot-ball. It is seriously to be questioned whether the strenuous grilling that a foot-ball player must undergo does not actually impair his ability to concentrate upon his studies.
If you undertake a course of exercise, by all means have it regular. Little is gained by sporadic exercising. Adopt the principle of regularity and rhythmize this important phase of bodily activity as well as all other phases.
In concluding our discussion of physical hygiene for the student, we cannot stress too much the value of relaxation. The life of a student is a trying one. It exercises chiefly the higher brain centres and keeps the organism keyed up to a high pitch. These centres become fatigued easily and ought to be rested occasionally. Therefore, the student should relax at intervals, and engage in something remote from study. To forget books for an entire week-end is often wisdom; to have a hobby or an avocation is also wise. A student must not forget that he is something more than an intellectual being. He is a physical organism and a social being, and the well-rounded life demands that all phases receive expression. We grant that it is wrong to exalt the physical and stunt the mental, but it is also wrong to develop the intellectual and neglect the physical. We must recognize with Browning that,
"All good things Are ours, nor soul helps flesh more, now, than flesh helps soul."